Question

If the common ratio of a G.P. is `2/3` and sum of its terms to infinity is 12. Find the first term.

Answer 1

r = `2/3` sum to infinity = 12          …[Given]

Sum to infinity = `"a"/(1 - "r")`

∴ 12 = `"a"/(1 - 2/3)`

∴ a = `12 xx 1/3`

∴ a = 4.